The Accessibility Shortcut
You can set the Digital Crown to turn either VoiceOver or Zoom on or off with a triple-click.
Set the Accessibility Shortcut. Open the Apple Watch app on iPhone, tap My Watch, go to General > Accessibility > Accessibility Shortcut, then choose VoiceOver or Zoom.
Use the shortcut. Press the Digital Crown quickly three times. Triple-click the Digital Crown again to turn off the accessibility feature.